(A) proportional-share scheduler for multimedia applications

Abstract

This thesis presents a proportional-share CPU scheduler for multimedia applications in a general-purpose workstation environment. Our scheduler is based on the stride scheduler, which may be adequate to conventional tasks, but is insufficient for multimedia applications. In order to support multimedia applications as well as conventional tasks, we have extended and revised the stride scheduler. New scheduling parameters are introduced to specify timing requirements of multimedia applications. Through the use of the rate regulator, the accuracy error of the revised scheduler is reduced to O(1) while that of the stride scheduler is O(N), where N is the number of runnable tasks. The concept of Adaptable-share Group and Fixed-share Group is proposed to represent both an absolute share and a relative share efficiently. The proposed scheduler is compared and evaluated using a simulation study. We carried out some experiments in underload and overload situations. The simulation results show that the proposed scheduler achieves improved accuracy, flexibility and adaptability, so successfully accommodates both multimedia applications and conventional tasks.